Overview
The Alloy Metal Ring is to all outward appearances a very basic cock ring. Don't let appearances deceive, though, as this basic, $12 option has potential that far outstrips its meager price point. While I was not able to utilize it to its full extent (reasons given below), this has serious potential for some fun times.

Design & Use
First and foremost, this is a WIDE ring of what seems to be well machined aluminum alloy. The width is an important consideration - while it doesn't seem all that much wider than many rings on the market, the design is such that the package is pushed entirely forward. This means that the wearer's balls are now raised up and pushed forward out of normal position. Some individuals may need to experiment with scrotal stretching before being able to use this product, as it requires a certain amount of stretch in the scrotum and Vas Deferens to pull the balls through before pulling the penis through.

Once the threading process is accomplished, the result is visually striking - the scrotum is now lined up with the underside of the penis (unless the user has done something drastically wrong - or right, if he or his partner are into CBT), lifting them into, shall we say the flight path? This means that every stroke is shortened by the length of the ring + the length of the testes, but that the scrotum and testes will be hitting home on ever deep stroke. I can't speak for how this would feel for a woman, but I would imagine that in doggy-style, this could be a welcome additional bit of clitoral stimulation.

Of course, the consequence is that very rough sessions may cause some tenderness for the man afterward. I would suggest starting out slow and steady at first to get the feel for having the package re-aligned in such a dramatic way.

Sizing and Considerations
I went with the 1.75" option, which is generally what I get when I want a snug cock ring. This may have been a mistake on my part, as I underestimated how...challenging it can be to thread both of my testes and my penis down a 3/4" long tube of aluminum. I would NOT recommend threading the balls with lube on your hands - it's hard enough to get the boys to both go down the tube as it is, and adding lube would just make them even harder to put through the hole. A little lube on the penis wouldn't be a bad thing, though - with the full width of the scrotum now occupying the tube, it will most likely be a snugger fit than most cock rings.
This is why I say it might be a mistake to go with your normal size choice - if you pause and consider a normal cock ring compared to this tube, you're actually putting much more material through the tube before it opens up again. Careful consideration is warranted. Then again, at this price point, you can't really go wrong in buying your normal size and a size up for testing purposes.

Other considerations - this is a metal ring, and aluminum has a rather low specific heat. It doesn't take much to warm, and those with biological testes know what happens when they are exposed to cold. Do yourself a favor and warm it up in some warm water or carrying it in your pocket for a little while before putting it on, and you should have an easier time. Some discomfort is probably to be expected when you first get the ring on if you've never used a ring like this, as you're stretching your testes and the associated attachments in a new direction. Also, be aware that you may inadvertently chase one of your testes into a "tucked" position (don't know what I'm referring to? Look up "wearing a gaff") while trying to get the second testis into the tube. And finally, be aware that getting OUT of the tube will be an interesting endeavor. It's safe enough for general wear (I wore one for about 6 hours one day), but you do eventually want to pull your stuff out of there.

Full disclosure - I've only had solo experience with this toy to date. I was surprised by the rather intense erections that this ring can produce - almost to the point of painful sensitivity - but also at how erotic it seemed with having my balls sticking forward. My key wish in personal experience with the device is that I were waxed - both to amplify the visual effect and to avoid pulling hairs in putting the ring on. Aside from that, I'm very pleased with this ring, and it has rapidly become one of my favorites as a display piece. For personal gratification, it's just a slight bit too tight and too sensitive, but that may change as I get used to the piece. Overall, though, I consider this to be one of the finest investments I have made.